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In This Issue • From the State Climatologist The North Dakota Climate Bulletin is a digital • Weather Highlights: Seasonal quarterly publication of the North Dakota State Summary Climate Office, College of Agriculture, Food • Historic North Dakota Winter Systems, and Natural Resources, North Dakota Precipitation and Temperature State University, Fargo, N.D. Since 1895 • Storms and Record Events: State Tornado, Hail and Wind Reports The overall spring average temperature was 1.3 degrees cooler and Record Events than average, which would make it the 61st coolest spring on • Outlook: Summer 2020 record. Precipitation-wise, the statewide accumulation was 2.14 • Hydro-Talk: Another Tale of Two inches drier than average, which would make it the ninth driest Halves spring on record. Considering the past five months, it also ranks • Science Bits: Just a Spring Dust among the sixth driest such period on record. The drier-than- Devil or is it a “Gustnado”? average season was well-received, especially along the Red River Produced by Valley of the North, where the flood-damaged areas got a chance Adnan Akyüz, Ph.D. to dry for necessary field work. Overall, a total of 167 records, State Climatologist including temperature- and precipitation-related occurrences across the state, were tied or broken. Graphics NCEI, NDSCO, NDAWN, NOAA, Dry conditions in the western parts of the state caused moderate CPC, USDM, UCAR drought in the middle of the season. A summary of the statewide drought sysnopsis can Contributing Writers be found in the Hydro- R. Kupec Talk portion of this A. Schlag bulletin. G. Gust Detailed monthly North Dakota State Climate Office climate summaries for www.ndsu.edu/ndsco March, April and May, along with several North Dakota State University other local resources for climate and weather information, can be Lonely tree. (Vern Whitten Photography) accessed at www.ndsu.edu/ndsco. Adnan Akyüz, Ph.D., North Dakota State Climatologist 1 Precipitation Using analysis from the National Centers for Environmental Information (NCEI), the average North Dakota precipitation for the spring season (March 1 through May 31, 2020) was 2.44 inches, which was 1.11 inches greater than the last season (winter 2019-20), 1.52 inches less than last spring (spring 2019) and 2.14 inches less than the 1981-2010 average spring precipitation (Table 1). This would rank the spring of 2020 as the ninth driest (118th wettest) spring since Figure 1. Precipitation percent of normal in spring 2020 for North Dakota. such records began in 1895. (High Plains Regional Climate Center, HPRCC) The numbers less than 100 in Figure 1 are shaded in yellow and red to depict the region with below- average rainfall. In contrast, the numbers that are greater than 100 in the same figure are shaded in green, blue and purple to depict the region with above-average rainfall. The greatest seasonal precipitation accumulation of the season was 4.63 inches, recorded in Ellendale, Dickey County. The greatest seasonal snowfall accumulation was 19 inches, recorded in Grand Forks, Grand Forks County. Based on historical records, the state average spring precipitation showed a positive long-term trend of 0.25 inch per century during this period of record since 1895. The lowest and highest seasonal spring precipitation for the state ranged from 1.3 inches in 1934 to 9.64 inches in 1896. The “Historical Spring Precipitation for North Dakota” time series (Figure 2) shows a graphical depiction of these statistics. 2 Figure 2. Historical spring precipitation time series for North Dakota. Table 1. North Dakota Spring Precipitation Ranking Table1. Period Value Normal Anomaly Rank Wettest/Driest Record Since Year Spring 2.44” 4.58” - 2.14” 9th driest Driest since 1980 1.3” (1934) 2020 118th wettest Wettest since 2019 9.64” (1896) 1 NOAA National Centers for Environmental Information, Climate at a Glance: Statewide Time Series, published December 2019. Retrieved on Dec. 11, 2019, from www.ncdc.noaa.gov/cag. 3 Temperature The average North Dakota temperature for the season (March 1 through May 31) was 40 F, which was 24.4 degrees warmer than the last season (winter 2019-20), and 2.7 degrees warmer than last spring (2019 season). It was 1.3 degrees cooler than the 1981-2010 average spring temperature, which would rank spring 2020 as the 61st coolest (66th warmest) spring since such records began in 1895 (Table 2). Figure 3 shows the departure from normal Figure 3. Temperature departure from normal in spring 2020 for North temperature distribution Dakota. (North Dakota Agricultural Weather Network) geographically. The negative numbers in Figure 3 are shaded in green and blue to depict the region with below-average temperatures. In contrast, numbers that are equal to or greater than zero in the same figure are shaded in orange and red to depict the region with average to above-average temperatures. Based on historical records, the average spring temperature showed a positive trend of 0.2 degree per decade since 1895. The lowest and highest seasonal spring temperatures for North Dakota ranged from minus 31.5 F in the 1899 season to 48.1 F in the 1977 season. The “Historical Spring Temperature for North Dakota” time series (Figure 4) shows a graphical depiction of these statistics. 4 Figure 4. Historical spring temperature time series for North Dakota. 2 Table 2. North Dakota Spring Temperature Ranking Table . Period Value Normal Anomaly Rank Warmest/Coolest Record Since Year Spring 40 F 41.3 F -1.3 F 61st coolest Coolest since 2019 31.5 F (1899) 2020 66th warmest Warmest since 2017 48.1 F (1977) 2 NOAA National Centers for Environmental Information, Climate at a Glance: Statewide Time Series, published December 2019. Retrieved on Dec. 11, 2019, from www.ncdc.noaa.gov/cag. 5 Drought: The state had no dryness getting into spring by utilizing excessive soil moisture left over from the previous fall and winter. However, as the season progressed, precipitation was lacking in western North Dakota while major flooding was observed along the Red River Valley of the North. By the end of the season, 31% of the state was in moderate drough. Figure 5 below shows the drought conditions in the beginning and the end of spring. Figure 6 shows the drought intensity and coverage in a time scale. Both of the figures show no drought conditions spatialy and temporally. Figure 5. Drought Monitor map comparison for North Dakota in the beginning (on the left) and at the end (on the right) of spring 2020. (U.S. Drought Monitor) Figure 6. Statewide drought coverage in percentage and intensity (DO, D1, etc.) in a time scale representing the state from the beginning to the end of the season, with a one-week resolution in spring 2020. 6 Table 3. The numbers in the table below represent the number of tornados and hail and wind events accumulated monthly and seasonally. March April May Seasonal Total Tornado 0 0 1 1 Hail 2 1 2 5 Wind 1 0 0 1 Total 3 1 3 7 March April May North Dakota Storm Events North Dakota Storm Events North Dakota Storm Events Figure 7. Geographical distribution of the storm events in the table above in each month. The dots are color-coded for each event (red: tornado; blue: wind; green: hail). Table 4. The numbers in the table below represent the number of select state record events (records broken or tied) accumulated monthly and seasonally. Category March April May Seasonal Total Highest daily max. temp. 7 0 0 7 Highest daily min. temp. 2 1 3 6 Lowest daily max. temp. 1 36 1 38 Lowest daily min. temp. 1 43 20 64 Highest daily precipitation 8 12 3 23 Highest daily snowfall 7 18 4 29 Total 26 110 31 167 7 Summer 2020 Outlook By R. Kupec3 Dry and cool conditions could be found across North Dakota this spring. Across the state, most locations were 1 to 4 degrees below average for the season. The colder spots were in portions of the Red River Valley, while spring was not as cold in the western portion of the state. The diminished precipitation that began with the start of 2020 continued into the spring season. Moisture deficits of 2 to 5 inches below average were common across the state. The spring outlook called for near-average precipitation and average to slightly above average temperatures. An unusually strong jet stream across the southern U.S. held through the spring season. Usually this jet stream would migrate north during the spring to allow moisture from the Gulf of Mexico into North Dakota. That rarely happened this spring. Now, in early June, moisture is finally streaming north, resulting in several rounds of thunderstorms with heavy rain. In the southern Pacific, the El Niño/La Niña pattern has entered a neutral phase and is showing signs of developing a weak La Niña. The northern Pacific, like last summer, remains warm. Given those factors, expect this summer to see average to slightly below average precipitation and temperatures near seasonal normals. The current Climate Prediction Center (CPC) Summer Outlook has a similar outlook for temperatures, calling for an equal chance of above- or below-average temperatures for roughly the eastern two-thirds of the state. For the western one-third, the CPC is predicting a warmer than average summer (Figure 8a). The CPC precipitation forecast is starkly different, calling for above-average rainfall in much of the east and south-central parts of the state. It also expects drier than average conditions in areas along the Montana border (Figure 8b). The next 90-day outlook from the CPC should be available after June 18 at www.cpc.ncep.noaa.gov/products/predictions/90day.
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